1. Technical Field
The present invention relates to a photomask, a method of manufacturing the same, and a method of manufacturing an electronic device, and particularly relates to a method of manufacturing a photomask using a droplet ejection method.
2. Related Art
In the manufacturing process for electronic equipment such as semiconductor devices and various displays, photolithographic techniques have conventionally been used for producing thin-film patterns, with a method being adopted of transferring a photoresist pattern onto a photosensitive material such as a photoresist applied on a substrate.
A common procedure of manufacturing a photomask is to manufacture a master mask by repeating reduced projection exposure after forming a reticle based on CAD data, and then mass-producing a working mask (copy).
A specific method of manufacturing a working mask that is generally used is to form, for example, a chromium evaporated film on a transparent substrate, such as quartz glass, transfer a reticle pattern using a photolithographic technique similar to the manufacturing process for a semiconductor device, which involves resist application, exposure, development, etching, and resist removal, and then pattern the chromium film (refer, for example, to Japanese Unexamined Patent Application, First Publication No. H09-73166). Other methods, such as electron-beam direct-writing are also in use.
As a result of actually manufacturing an electronic device using the completed photomask, the need may arise to correct the pattern of the photomask. Alternatively, as is the case with the semiconductor device known as an Application Specific Integrated Circuit (ASIC), semifinished products are prepared equipped with a number of circuit blocks having functions specified in advance, with wiring forming and corrections needed at the time of acquiring the customer specifications as in the case of manufacturing a semi-custom IC meeting the customer requirements by changing only the wiring.
Since, in the conventional method, a request for pattern formation, correction, alteration and the like involves redoing the entire photolithographic process starting from correcting the reticle and manufacturing a new photomask, considerable time and cost are expended.